Secondhand smoke (SHS) is recognized as a class A carcinogen and has no safe level of exposure. SHS is estimated to contribute to over 3,000 lung cancer deaths in non-smokers annually. With widespread legislation restricting smoking in workplaces and other public venues, most of the U.S. public now live in states with laws to protect against SHS exposure. Yet, the primary place in which involuntary exposure to SHS still occurs is in workplaces and public places on federally-recognized tribal reservations. Nonsmokers from the Oglala Sioux Tribe, a Lakota tribe from South Dakota, disproportionately share the burden of SHS, especially in their workplaces and public places. Our own recent findings show that Lakota adult nonsmokers have cotinine levels equal to those regularly seen in active smokers. With smoking prevalence as high as 50% among this population, the consequences of SHS already manifest among the Lakota include high prevalence of childhood asthma and sudden infant death syndrome. Further complicating matters, the expanded use of commercial tobacco products for ceremonial and cultural practices is creating challenges not typically seen in non-American Indian communities. Therefore, eliminating SHS exposure in a culturally appropriate manner is a fundamental step in decreasing morbidity and mortality among members of the Oglala Sioux Tribe and other Northern Plains Tribes. Our primary study objective is to develop and test a culturally informed smoke-free advocacy training intervention to encourage Lakota opinion leaders to more effectively advocate for their tribe to generate smoke-free policies addressing SHS exposure in workplaces and public places We propose to conduct a randomized, wait-list controlled pragmatic trial to develop, implement and evaluate a culturally informed SHS advocacy training module versus standard smoke-free policy print materials. Therefore, our Specific Aims are to 1) Assess knowledge, attitudes and beliefs about secondhand smoke exposure and perceived facilitators and barriers to adoption of smoking restrictions on the Pine Ridge Sioux Reservation; 2) Use a highly participatory, culturally informed approach to design, implement, evaluate and disseminate an advocacy training intervention for smoke-free policies among adults living on the Pine Ridge Indian Reservation; and 3) Determine the effect of the intervention on health-related quality of life, SHS risk perception, SHS exposure and smoking 6-months after implementation of the advocacy intervention. The results from this study will have many programmatic and policy-related implications. Lakota communities will have a better understanding of the impact of SHS exposure, and recognition that they have the capability to create a healthier environment. This innovative study design is also scalable to other low- resourced settings and populations. Finally, our community-based, participatory methods will strengthen our tribal partner's knowledge, expertise, and support for intervention research.